Goggles used for skiing tend to fog due to the low environmental temperature and the high humidity of the air captured between the goggles and a user's face. Fogging may be avoided by using goggles having inner and outer lenses defining an air cavity therebetween. The air cavity insulates the inner lens from the environment such that it does not become cold enough to cause condensation.
The air cavity typically must be vented such that changes in environmental pressure due to changes in altitude do not cause the lenses to bulge or break. In typical double lens goggles, the vent opens into the volume between the goggles and the user's face. Unfortunately, the air between the lens and the wearer's face is typically very moist, primarily because of the wearer's perspiration. As a result, air passing from the space behind the lens into the cavity between the lenses is laden with moisture which can condense on the inner surface of the outer lens.
A goggle could avoid introducing moisture laden air from behind the lens into the space between the lenses by venting the lens to the external environment through the outer lens. However, venting the inter-lens space through the outer lens tends to permit the entry of water through the vent into the space between the lens. Some goggles use a thin sheet of anhydrous material to cover a vent formed on the inner lens and thereby prevent the entry of water. However, the sheet is typically much larger than the vent and therefore occupies a substantial portion of the viewing area of the goggles. Furthermore, the thin anhydrous films are somewhat fragile and require complex housings such as are illustrated in U.S. Pat. No. 4,290,673 to Yamamoto.
In view of the foregoing it would be an advancement in the art to provide a compact, readily manufacturable vent for double lens goggles that reduces the possibility of fogging found in prior goggles.